1. Field of the Invention
The present invention relates to a reduction/enlargement processing system for an image processing apparatus of the type in which a line sensor is moved in a secondary scan direction while an image on an original is read by the line sensor in a main scan direction, the image data thus read is converted into a digital gradation data signal, the gradation data signal is appropriately processed for reproducing the original image, and the reproduced image is recorded.
2. Prior Art Description
In recent days, the copying machine is used in a variety of fields. With this, the requests for the outputted copies have been increased in number and variation. Most of the recent copying machines are provided with the reduction/enlargement (R/E) function. This function allows a user to reduce and enlarge an image on an original at a desired magnification and to copy the image at that magnification on a paper of a desired size. In the copying machine with a plurality of paper trays, for example, a user can select the paper size and the magnification as he desires.
One of the conventional approaches to realize the R/E function is to store the image data into a memory capable of storing the image data on a sheet of original, and to use a software technology for the R/E processing. A second approach is to store the image data in a memory of one line, and to vary the frequency of a sampling clock signal, viz., to quick or slow the clock signal, for the R/E processing. A third approach is to thin out the image data in a simple manner for the reduction and to interpolate the image data in an insert manner for the enlargement.
The disadvantages of the first approach is to require a large amount of memory capacity, and to take much time for the R/E processing because it is performed by the solftware. The second approach is disadvantageous in that there is a limit in a range of a magnification, for example, extremely large and small magnifications cannot be set. In the third approach, the image data or pixels are thinned out for the reduction and the same pixels are additively inserted for the enlargement. This approach is simple in the processing, but a reproduced picture by the approach is poor in picture quality because it suffers from Moire and the details of the picture is coarse.